Low-Frequency Noise Assessment of Silicon Passivated Ge pMOSFETs With TiN/TaN/ $\hbox{HfO}_{2}$ Gate Stack

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The low-frequency noise of pMOSFETs fabricated in epitaxial germanium-on-silicon substrates is studied. The gate stack consists of a TiN/TaN metal gate on top of a 1.3-nm equivalent oxide thickness <formula formulatype="inline"> <tex>$\hbox{HfO}_{2}/\hbox{SiO}_{2}$</tex></formula> gate dielectric bilayer. The latter is grown by chemical oxidation of a thin epitaxial silicon film deposited to passivate the germanium surface. It is shown that the spectrum is of the <formula formulatype="inline"><tex>$\hbox{1}/f^{\gamma}$</tex></formula> type, which obeys number fluctuations for intermediate gate voltage overdrives. A correlation between the low-field mobility and the oxide trap density derived from the <formula formulatype="inline"><tex>$\hbox{1}/f$</tex></formula> noise magnitude and the interface trap density obtained from charge pumping is reported and explained by considering remote Coulomb scattering. </para>